The Parkinson's app, called Parkinson mPower (which stands for Mobile Parkinson Observatory for Worldwide, Evidenced-based Research), was developed by the non-profit research organization Sage Bionetworks in partnership with two University of Rochester physicians, Dorsey and Karl Kieburtz, and Aston University mathematics professor Max Little.

For example, comparing the tests of people who have Parkinson's and who use the app to the results of people who decided to join the app as part of the control group, Williams says that researchers made a startling observation:

Amongst the people who signed up as part of the control group, some of them exhibited symptoms similar to those who have Parkinson's. This could mean several things, including — potentially — that some of the people in the "control" group may have the disease as well. Since ResearchKit isn't a legal diagnostic tool yet, these results are still very preliminary. Plus, the study was only observational, meaning the researchers have no direct control over the experiment (they can't assign some people to develop Parkinson's and others to not develop it) and simply observe the way participants use the app.

Another valuable data point comes from looking at how people's medication affects their test results. After someone with Parkinson's takes their medicine, for example, that person should ideally have an easier time completing the app's tests, which include recording their voice and tapping their phone's screen as fast as they can. Subtle voice changes in tremor and volume as well as changes in dexterity have been shown to be a good way to measure the severity of Parkinson's symptoms, according to the University of Rochester Medical Center.

For many of the app's recent users who reported taking their medicine regularly, however, their test results did not appear to improve significantly, said Williams.

That's incredibly useful data for patients and doctors who want to see what effect — if any — their medication is having.

"If we only got these two learnings out of this app, it would already be worth it," Williams says.

In addition to its data on Parkison's, said Williams, another app called the asthma app is helping researchers at Mount Sinai pinpoint different triggers for asthma.

In Texas, for example, heat came up as one of the main possible triggers for asthma in people who use the app. In New York, on the other hand, the most popular trigger amongst users appeared to be anger.

Getting that information only took researchers weeks and months instead of years, like it usually would, Williams said.